Time Zones/Transcript
Transcript Text reads: The Mysteries of Life with Tim & Moby Tim and Moby are flying together in a passenger plane. Moby taps Tim on the shoulder and hands him an envelope. MOBY: Beep. TIM: Okey-doke. Tim reads from a typed letter. TIM: Dear Tim and Moby, how many time zones are there? From, Upton. The Earth is divided into 24 time zones, one for every hour of the day. The time zones run north-south, each taking up about 15 degrees of longitude. A world map shows the time zones Tim describes. Each time zone band is approximately fifteen degrees wide. Many of the time zones are divided in a jagged way. MOBY: Beep. TIM: Well, longitude lines, or meridians, are the imaginary lines that run north-south between the two poles. An image shows a globe with the longitude lines that Tim describes. The North Pole and South Pole are labeled. TIM: There are 360 of these imaginary lines, called degrees. Points along the same meridian share the same time. A world map with longitude lines illustrates what Tim describes. Graphics show that New York City and Bogotá, Colombia, share a meridian and are in the same time zone. MOBY: Beep. TIM: Well, I guess they could do that, but I think 360 different time zones would be really confusing. So each 15-degree wedge of the Earth is assigned a time based on the meridian running through its middle. The world map is broken into time zones, with clocks showing the differing hours at the same point in time. TIM: There are a few exceptions, but most time zones are exactly one hour ahead of the time zone to the west of it and one hour behind the time zone to the east of it. A map of the United States illustrates the nation's four time zones. From west to east, they are: Pacific Time, Mountain Time, Central Time, and Eastern Time. When Pacific Time is 12:55, Mountain Time is 1:55, Central Time is 2:55, and Eastern Time is 3:55. TIM: For every time zone this plane crosses moving east, I have to set my watch ahead one hour. And if we were flying westward, I'd have to set my watch back an hour for every time zone we'd cross. A plane flies east across the map of the United States. As the plane crosses a time zone eastward, a watch shifts an hour forward. As the plane turns and crosses time zones westward, the watch moves an hour backward. MOBY: Beep. TIM: Why can't it just be the same time everywhere? Well, that would be a lot easier to keep track of, but it wouldn't make a whole lot of sense. To understand why we need time zones, we need to do a little astronomy. An image shows Earth from space. TIM: See, the earth rotates, or spins on its axis, one full time every 24 hours. The earth spins as a clock charts the time. After one full rotation, the clock reads: 24 hours, 0 minutes. TIM: The earth's rotation makes the sun appear to rise, set, and move across the sky. An animation shows the sun rising, crossing the sky, and setting over a wilderness area. The sunset leaves the area with a moonless, starry sky. TIM: The sun hits different parts of the earth at different times of the day, making it light in some places when it's dark in others. Animations of the rotating earth, relative to the sun, and the wilderness area illustrate the day/night cycle as Tim describes it. MOBY: Beep. TIM: I'm, I'm gettin' there. Guess how fast the earth spins. MOBY: Beep. Moby shrugs. TIM: Okay. It spins at a rate of 15 degrees of longitude per hour. An animation shows Earth rotating 15 degrees in one hour. TIM: Do you see the connection? Fifteen degrees per hour corresponds to 15 degrees per time zone. Images compare fifteen degrees on the rotating Earth with fifteen degrees on the World Time Zone map. TIM: Because the earth spins from west to east, the day starts earlier the farther east you live. Earth spins with a compass over it to show its rotation west to east. TIM: That's why eastern time zones are ahead of western ones. When the sun rises in New York, it's still dark in L.A. An animated U.S. map shows the sun passing over the country. Animations compare the sun's path in New York City and Los Angeles. The sunrise in Los Angeles happens later than the one in New York. TIM: But because we have time zones, the sun rises and sets at the same local time in both cities. An animation illustrates sunrises in New York and Los Angeles. Both occur at 6:03 AM local time, but three hours apart in real time. MOBY: Beep. TIM: Meaning you can count on the fact that's it's gonna be light enough to walk to school or drive to work by, say, 7 AM in both cities. An image shows a sunny morning in New York. Text reads: 7:00 AM Eastern Time. A second image shows a sunny morning in Los Angeles. Text reads: 7:00 AM Pacific Time. TIM: Time zones deal with more than just science and geography. They help us manage our lives. If you look at the map of time zones, you'll see that most of them are kind of jagged here and there. The world time zone map illustrates what Tim describes. TIM: That's because those meridians run through geographical borders. Country outlines appear on the world time zone map to illustrate how meridians run through countries. TIM: Governments will often fudge the meridians' boundaries so that people in the same state or country don't have to live in different time zones. A U.S. time zone map demonstrates Tim's point. None of the time zone borders run straight down a meridian. TIM: The Prime Meridian, which runs through Greenwich, England, at 0 degrees longitude, is the reference point for all other times on Earth. The world time zone map shows Greenwich, England on the Prime Meridian. TIM: The time at the Royal Greenwich Observatory is known as Universal Time, or sometimes Greenwich Mean Time. An image shows the Royal Greenwich Observatory and abbreviates Greenwich Mean Time as GMT. The plane carrying Tim and Moby lands. The two stand in an airport, holding their luggage. The airport is quiet and empty. TIM: Huh. I thought Mom was supposed to be picking us up. MOBY: Beep. TIM: What time is it? I... I'm not sure. Category:BrainPOP Transcripts Category:BrainPOP Social Studies Transcripts Category:BrainPOP Science Transcripts